1. Field of the Invention
The present invention relates to a process and apparatus for manufacturing decorative papers and/or panels for flooring or surfacing of furniture, walls, finish foils, filter papers, kraft papers etc., with powder aminoplasts and/or phenoplasts and/or mixtures as such and/or mixed with additives.
In particular, the invention relates to the manufacture of decorative papers, finish foils, kraft papers for high and low pressure, panels comprising these products, as well as panels made of plaster or other materials for walls or false ceilings and filter papers.
2. Description of Related Art
As is known, decorative papers for manufacturing panels for flooring or surfacing of furniture, walls, etc. are commonly obtained from printed and/or coloured papers, which are impregnated in a liquid solution of polymeric resins (typically melamine resins) or mixtures of resins and other compounds; after being impregnated and dried, the papers are then normally coated with mixtures of polymeric resin containing granular substances such as corundum and/or glass microspheres, they are dried again, possibly further coated with other protective and/or finishing compositions and dried again. The papers prepared thereby are therefore mainly used cut in sheets and pressed onto chipboard wooden or MDF panels or coupled with phenolic paper to obtain panels for the furniture sector, or planks for the flooring sector, or panels for the wall surfacing sector, etc. For the purpose of this description the terms “polymerization” and “polymer” are to include also “polycondensation” and “polycondensate”, respectively.
The current production system employs long lines mainly formed by an unwinder, an impregnation bath, a drying oven, a first spreader, an oven, a second spreader, another oven, possibly a third spreader and a corresponding oven, a cooling unit, a winder, and/or a cutter and a paper stacking unit.
These lines are therefore very long and expensive as far as energy consumption is concerned, they produce large amounts of starting and finishing scraps and display difficulties in stopping production in progress.
A more recent technology for manufacturing panels for flooring or surfacing of furniture, walls, floors etc., the so-called direct printing, avoids the use of decorative papers, as the desired picture is directly printed onto the ready-made panel. The panels, which are appropriately treated and prepared (in particular by means of a treatment for sealing surface porosity, and possibly to lend a uniform background colour), are coloured/decorated along the line (by means of indirect single-colour or multi-colour gravure printing systems, or by means of digital printers) and dried, thus obtaining a ready-to-use product, after a final coating of UV or IR polymers to lend protection and surface hardness.
Although certainly simpler with respect to traditional methods based on the impregnation and coating of the supports and subsequent pressing, this technology does not allow to apply components increasing surface resistance to abrasion and scratching etc. on surfaces prepared in this way, nor does it allow to obtain structured surfaces (i.e. reproducing wood veinings, surface profiles in stone, etc), without using already previously structured surfaces, on which however final colours/pictures may then only be printed by a digital printing technique that implies low production rates and a quality which is not completely satisfactory.